The Start-Up dialog box is displayed when first starting ModelMuse. It prompts the user either to start a new project, open an existing ModelMuse project, or import a MODFLOW-2005 or MODFLOW-NWT model. The five most recently opened files will be listed among the choices.

If the user chooses to start a new project, the user will be prompted for Geo-reference data and, for MODFLOW models, a description of the model. The data include the starting date and time of the model, the projection which may be in either epsg or proj4 format. For hypothetical models, the projection should be listed as "NA." If the model units are not part of the input for the model the user will be prompted for the length and time units. The Geo-reference data can also be edited in the Geo Reference dialog box. The model description can be edited in the MODFLOW Options dialog box,

Next the Initial Grid dialog box will be displayed for MODFLOW, PHAST, and WellFootprint models. The Initial Model Area dialog box will be displayed for new SUTRA models. If the user chooses to import a MODFLOW-2005 or MODFLOW-NWT model, the Import MODFLOW-2005 or -NWT model dialog box will be displayed.